Shell backpack



FIG. 1 is a top, left rear perspective view of a shell backpack showing my new design;

FIG. 2 is a bottom, right, front perspective view of the design of FIG. 1;

FIG. 3 is a rear view of the design of FIG. 1;

FIG. 4 is a front view of the design of FIG. 1;

FIG. 5 is a right side view of the design of FIG. 1;

FIG. 6 is a left side view of the design of FIG. 1;

FIG. 7 is a top view of the design of FIG. 1; and,

FIG. 8 is a bottom view of the design of FIG. 1.

The structural elements depicted by broken lines have been shown for the purpose of illustrating portions of the shell backpack that form no part of the claimed design. 

CLAIM The ornamental design for a shell backpack, as shown and described. 